After suffering from cystitis, if it is not treated in time, the condition will worsen further, leading to obvious symptoms of frequent urination, urgency, and pain during urination. Severe cases may be accompanied by significant hematuria and pyuria, and even chills and high fever. If still not treated promptly, bacteria are very likely to retrogradely enter the kidneys through the ureters, causing acute pyelonephritis and leading to symptoms of back pain in patients. Severe cases can affect kidney function and even be life-threatening. Additionally, if the inflammation persists, it can lead to contractions of the bladder, reduced bladder capacity, and subsequent significant lower abdominal pain. It may even cause reproductive system inflammations such as prostatitis and orchitis in male patients.